The alternative approach, led by Huawei and Vodafone was for a “clean sheet“ approach. This was a solution which did not have the intelligence to coexist with 4G networks, but required operators to set aside a small amount of spectrum for it, (which could be a guard band), specifically reserved for IoT traffic. As the chips didn’t need to be aware of any other 4G traffic, they could be much simpler and hence much cheaper. It’s a cleaner approach, but one which goes against the traditional network approach of making complex hardware which can work on any band around the world. Network operators typically prefer the complex hardware approach, as it passes the problem of global interoperability onto the chip and protocol stack companies. Whatever the operators do with their networks, regardless of the frequency bands they own, things just work. But it raises the cost of hardware.